1102891 - GLSL break statement ignored in shader

Status: RESOLVED FIXED

(Core :: Graphics: CanvasWebGL, defect)

Description

[Glynn Clements]

Consider a fragment shader like:

#define MAX_POINTS 16

uniform int npoints;

..for (int i = 0; i < MAX_POINTS; i++) {
......if (i >= npoints)
..........break;
......// loop body
..}

The intent is to perform a variable number of iterations in spite of the GLSL-ES restriction that iteration counts must be fixed at compile time (appendix A.4).

The "break" statement appears to be silently ignored, i.e. the loop body is execute on all iterations.

In this case, replacing the "break" with "continue" provides a sufficient workaround (once i>=npoints becomes true, it will remain true for all further iterations). But "break" statements are valid in the OpenGL ES 2.0 version of GLSL.

Hardware: AMD Radeon HD 7800 Series
OpenGL Driver Version: 6.14.10.12618

Comment 1

[Dzmitry Malyshau [:kvark]]

Sounds like an Angle issue to me, given that you are running Windows 7. I tried making a simple shader with such a loop and compiling it via Angle to HLSL, and I can see the `break` is still there in the right place, so it seems rather weird that you'd get this issue. Could you provide a test case?

Comment 2

[Glynn Clements]

I can't reproduce this in my current version of Firefox (40.0.3).

Comment 3

[Dzmitry Malyshau [:kvark]]

The reporter can't repro it any more, considering this fixed.